Large internal combustion engines, and in particular marine engines, are generally reversible since the torque to be transmitted is too large for it to be possible to use rotation reversing means of reasonable bulk and simple construction.
In known manner, the camshafts of these engines are provided with additional cams to modify the instants at which the admission and exhaust valves open, and also to modify the instants at which fuel is injected into the cylinders.
Each camshaft thus includes two cams per controlled member, one being for one direction of rotation and the other, which is angularly symmetrical to the first about a dead point of the crankshaft, being for the opposite direction of rotation.
The direction of rotation is changed by shifting the camshafts in translation when the engine is stopped. To pass from one cam to the other, the tappet cam-follower wheels slide over the cams without rotating, thus giving rise to considerable wear of the rolling paths on the wheels and on the cams.
The aim of the present invention is to avoid wear on the rolling paths and on the connections slopes of the cams by replacing said sliding without rolling by rolling without sliding. The force required to shift the camshaft is thus considerably reduced.